Therapy
Replacing saturated fat with walnuts or vegetable oils improves cholesterol without raising Lp(a), a 34-person crossover trial (J Nutr 2020)
Original title: Replacing Saturated Fats with Unsaturated Fats from Walnuts or Vegetable Oils Lowers Atherogenic Lipoprotein Classes Without Increasing Lipoprotein(a)
In a randomised, crossover, controlled-feeding trial, 34 adults at risk of cardiovascular disease (62% men, mean age 44 years, BMI 30.1) followed a 2-wk run-in diet then three 6-wk diets varying in fat source: a walnut diet, a walnut fatty-acid-matched diet, and an oleic-acid-replaces-ALA diet. Compared with the oleic-acid diet, the walnut diet lowered total cholesterol (-8.9 mg/dL, -5.1%, P<0.001), non-HDL cholesterol (-7.4 mg/dL, -5.4%, P=0.001), and LDL cholesterol (-6.9 mg/dL, -6.5%, P=0.001). Lipoprotein(a), cholesterol efflux capacity, and PCSK9 were unchanged across all three diets. The findings suggest replacing saturated fat with unsaturated fat from walnuts or vegetable oils improves the lipid profile without adversely affecting Lp(a) levels.
Original abstract
Background: Walnuts have established lipid-/lipoprotein-lowering properties; however, their effect on lipoprotein subclasses has not been investigated. Furthermore, the mechanisms by which walnuts improve lipid/lipoprotein concentrations are incompletely understood.
Objectives: We aimed to examine, as exploratory outcomes of this trial, the effect of replacing SFAs with unsaturated fats from walnuts or vegetable oils on lipoprotein subclasses, cholesterol efflux, and proprotein convertase subtilisin/kexin type 9 (PCSK9).
Methods: A randomized, crossover, controlled-feeding study was conducted in individuals at risk of cardiovascular disease (CVD) (n = 34; 62% men; mean ± SD age 44 ± 10 y; BMI: 30.1 ± 4.9 kg/m2). After a 2-wk run-in diet (12% SFAs, 7% PUFAs, 12% MUFAs), subjects consumed the following diets, in randomized order, for 6 wk: 1) walnut diet (WD) [57-99 g/d walnuts, 7% SFAs, 16% PUFAs [2.7% α-linolenic acid (ALA)], 9% MUFAs]; 2) walnut fatty acid-matched diet [7% SFAs, 16% PUFAs (2.6% ALA), 9% MUFAs]; and 3) oleic acid replaces ALA diet (ORAD) [7% SFAs, 14% PUFAs (0.4% ALA); 12% MUFAs] (all percentages listed are of total kilocalories ). Serum collected after the run-in (baseline) and each diet period was analyzed for lipoprotein classes and subclasses (vertical auto profile), cholesterol efflux, and PCSK9. Linear mixed models were used for data analysis.
Results: Compared with the ORAD, total cholesterol (mean ± SEM -8.9± 2.3 mg/dL; -5.1%; P < 0.001), non-HDL cholesterol (-7.4 ± 2.0 mg/dL; -5.4%; P = 0.001), and LDL cholesterol (-6.9 ± 1.9 mg/dL; -6.5%; P = 0.001) were lower after the WD; no other pairwise differences existed. There were no between-diet differences for HDL-cholesterol or LDL-cholesterol subclasses. Lipoprotein(a) [Lp(a)], cholesterol efflux, and PCSK9 were unchanged after the diets.
Conclusions: In individuals at risk of CVD, replacement of SFAs with unsaturated fats from walnuts or vegetable oils improved lipid/lipoprotein classes, including LDL-cholesterol, non-HDL cholesterol, and total cholesterol, without an increase in Lp(a). These improvements were not explained by changes in cholesterol efflux capacity or PCSK9. This trial was registered at clinicaltrials.gov as NCT01235832.
Summary written by lp-a.org from the published abstract; figures as published. Page updated 18 August 2026. Methods.